Sensor element, test device, and method for testing a data carrier having a spin resonance feature

Abstract

A sensor element is for testing a planar data carrier with a spin resonance feature. The sensor element includes a magnetic core having an air gap into which the planar data carrier can be inserted for testing purposes, a polarization device for generating a static magnetic flux in the air gap, and a resonator device for exciting the spin resonance feature of the data carrier to be tested in the air gap. The resonator device has at least two stripline resonators positioned at different positions in the air gap. The polarization device generates an in-homogeneous magnetic flux in the air gap so that the static magnetic flux has a first field strength at the position of a first stripline resonator and a second, different field strength at the position of a second stripline resonator.

1 .- 21 . (canceled) 
     
     
         22 . A sensor element for testing a planar data carrier having a spin resonance feature, comprising:
 a magnetic core having an air gap, into which the planar data carrier can be introduced for testing purposes,   a polarization device for creating a static magnetic flux in the air gap, and   a resonator device for exciting the spin resonance feature of the data carrier to be tested in the air gap,   wherein the resonator device contains at least two stripline resonators arranged at different positions in the air gap, and   the polarization device creates an inhomogeneous magnetic flux in the air gap in the magnetic core such that the static magnetic flux has a first field strength at the position of a first stripline resonator and has a second, different field strength at the position of a second stripline resonator.   
     
     
         23 . The sensor element according to claim  21 , wherein the stripline resonators of the resonator device are arranged in the shape of a one-dimensional array, in that the one-dimensional array is arranged in parallel with a gradient of the magnetic flux in the air gap. 
     
     
         24 . The sensor element according to claim  21 , wherein the stripline resonators of the resonator device form a multitrack arrangement having a plurality of parallel tracks, in which each track is formed by a one-dimensional array of stripline resonators,
 wherein the one-dimensional array of each track is arranged in parallel with a gradient of the magnetic flux in the air gap.   
     
     
         25 . The sensor element according to claim  21 , wherein the stripline resonators arranged at different positions in the air gap are each fed by a different signal source. 
     
     
         26 . The sensor element according to claim  21  wherein the air gap is bounded by two pole faces of the magnetic core,
 wherein one or both pole faces have a beveled and/or stepped embodiment. 
 
     
     
         27 . The sensor element according to  claim 26 , wherein the two pole faces make an angle with one another. 
     
     
         28 . The sensor element according to claim  21 , wherein the stripline resonators of the resonator device have the same resonant frequency, in that the stripline resonators moreover are designed and configured to test the spin resonance feature in the same spatial mode of the excitation field, in that the stripline resonators have an identical geometric shape. 
     
     
         29 . The sensor element according to claim  21 , wherein the aforementioned first field strength differs by at least 2% from the aforementioned second field strength. 
     
     
         30 . The sensor element according to claim  21 , wherein the sensor element comprises a modulation device for creating a time-varying magnetic modulation field in the air gap,
 wherein the modulation frequency is equally high at the location of each of the stripline resonators of the resonator device.   
     
     
         31 . The sensor element according to  claim 30 , wherein the modulation device is formed by an individual modulation coil arranged in the air gap, by an individual planar coil. 
     
     
         32 . The sensor element according to claim  21 , wherein the stripline resonators have a planar embodiment with a principal plane of extent which is perpendicular to the direction of static magnetic flux created by the polarization device. 
     
     
         33 . The sensor element according to claim  21 , wherein the air gap has a height of less than 10 mm. 
     
     
         34 . The sensor element according to claim  21 , wherein the sensor element comprises a ramp coil for creating a ramp function of the static magnetic flux. 
     
     
         35 . A test apparatus for testing a planar data carrier having a spin resonance feature, comprising:
 a sensor element according to claim  21  and   one or more signal source(s) by which the stripline resonators of the resonator device which are arranged at different positions in the air gap are fed.   
     
     
         36 . The test apparatus according to  claim 35 , wherein provision is made for a plurality of signal sources, by which one of the stripline resonators of the resonator device arranged at different positions in the air gap is fed in each case. 
     
     
         37 . The test apparatus according to  claim 35 , comprising a transport device which guides the planar data carriers to be tested along a transport path through the air gap in the magnetic core,
 wherein the transport path advantageously is parallel to a gradient of the magnetic flux in the air gap;   wherein the stripline resonators of the resonator device are arranged in the shape of a one-dimensional array, in that the one-dimensional array is arranged in parallel with a gradient of the magnetic flux in the air gap, wherein either the stripline resonators of the resonator device are arranged in the form of a one-dimensional array parallel to the transport path; or   wherein the stripline resonators of the resonator device form a multitrack arrangement having a plurality of parallel tracks, in which each track is formed by a one-dimensional array of stripline resonators, wherein the one-dimensional array of each track is arranged in parallel with a gradient of the magnetic flux in the air gap, wherein the stripline resonators form a multitrack arrangement in which each of the tracks is parallel to the transport path.   
     
     
         38 . The test apparatus according to  claim 37 , wherein the transport device is designed and configured for high-speed transport of the planar data carriers to be tested along the transport path. 
     
     
         39 . A method for testing a planar data carrier having a spin resonance feature by means of a sensor element or a test apparatus according to  claim 35 , wherein in the method
 a planar data carrier to be tested is guided along a transport path through the air gap in the magnetic core of the aforementioned sensor element,   wherein a plurality of stripline resonators of the resonator device are disposed in succession parallel to the transport path,   the polarization device is used to create an inhomogeneous magnetic flux in the air gap in the magnetic core, and a modulation device is used to create a time-varying magnetic modulation field in the air gap, and   the resonator device is used to excite the spin resonance feature of the data carrier to be tested.   
     
     
         40 . The method according to  claim 39 , wherein
 the data carrier to be tested is guided past the stripline resonators disposed in succession, and a temporal measurement series of the response signal from the spin resonance feature created post excitation is recorded by each of the stripline resonators,   measured data belonging to the same measured spot are in each case identified from the temporal measurement series of the stripline resonators,   spectral information about the spin resonance feature is derived from the identified measured data, and   the data carrier is assessed on the basis of the derived spectral information, with regards to authenticity and/or belonging to a data carrier class.   
     
     
         41 . The method according to  claim 39 , wherein the measured data are spatially resolved or spatially averaged. 
     
     
         42 . The method according to  claim 39 , wherein a spatially homogeneous ramp field is overlaid on the inhomogeneous static magnetic flux such that the entire static magnetic flux in the air gap varies over time between a minimum value and a maximum value,
 the spectral information is derived from the identified measured data taking account of the field strength of the static magnetic flux at the respective measurement time, and   the authenticity of the tested data carrier and/or the belonging of the tested data carrier to one of a plurality of data carrier classes with different spectral signatures is determined on the basis of the derived spectral information.